Alkylation of aromatics



Jan. 26, 1954 w. J. PALTZ ET AL ALxYLATIoN oF AROMATIcs Filed June 28,1950 Si!! 'linx- 'JnvenborS @nl tt'orneq Patented Jan. 26, 1954` UNITEDSTATES PATENT OFFICE ALKYLATION OF AROMATICS Walter J. Paltz, Fanwood,and Bruce R. Tegge,

Chatham,` N. J., assignors to Standard Oil Development Company, acorporation of Delaware Application June 2s, 195o, serial No. 170,754

8 Claims. (Cl. 2611-4571) This invention relates to improvements in thealkylation of aromatics by olens with recycling of alkylation productsthrough a heavier catalyst mixture. It is more particularly concernedwith methods of reducing catalyst sludge handling problems and productrecovery problems, which are accentuated in the manufacture of detergentalkylates by mono-alkylation of an aromatic compound with a C11 to C21olefin, using a system for recycling adequate amounts of the alkylationproduct including unreacted aromatic for mixing the reactants in properratio with minimal removal of catalyst from the reaction zone.

In the olefin alkylation of aromatics, relatively large volumes ofcatalyst, e. g. as a sludge or emulsion, were fed to a reactor, eitherupf-low or vdownflow, equipped with a mixing means, and the reactionmixture including the catalyst sludge or'- emulsion was Withdrawn to asettler, from which the catalytic sludge or emulsion was returned to thereactor to be mixed with additional fresh feed of olens and aromaticreactants in arquired ratio, the aromatic to olen reactant ratio in thefeed being kept high enough to increase-the desired amount ofmono-alkylation and reduce undesired side reactions, such aspoly'alkylation, polymerization, cracking and -isomerization Thus, inthe past with increased aromatic to olen feed ratios there have beenincreased difliculties in handling larger quantities of unreactedaromatic compounds, increased catalyst separation, handling, andrecirculating difli'culties, increased size of equipment, etc.

In accordance With the present invention, the described difficulties arelargely minimized or eliminated without detriment to the control of theselective alkylation reaction for obtaining tion catalysts, such as BFa,anhydrous liquid HF, mixtures of BFa with HF, and `With promoters suchas water or Oxy-organic compounds, and AlCls, more particularly certaincomplexes of A1013 which are only slightly miscible with thehydrocarbons.

reactants include benzene, alkyl benzenes, naphthalenes, phenols, andtheir homologs.

y The utility and advantages of the present invention are bestexemplified by the alkylation of aromatic hydrocarbons, such as benzeneand toluene with C11 to C21 olefins using an inorganic halide catalyst,such as aluminum chloride in a complex, to obtain selectivemonoalkylation of high selectivity required in the manufacture ofdetergent alkylates with a low cost catalyst land a minimum of corrosiveaction. The olefins may be obtained by cracking or dehydrogenating highboiling -paralins, by dimerizing, polymerizing, or

mono-alkylation, even thoughk the aromatic to olen feed sup-ply ratio ismaintained at a relatively low level, by employing a procedure of re-lrecovered by chemical treatments and fractiona` tion. Thus, theseparation of unreacted aromatic from alkylate lproduct for return tothe f reactor is also greatly simplified While the yield rate isundiminished.

There are various aromatic and olenic reactants which may be used in thealkylation reactions with the various 1 inorganic halide alkylal.

i preferably downwardly directed to obtain the best copolymerizing lowerolens, e. g. propene, butenes, hexenes, etc.

- The method Will be described with reference to a ilow plan in theaccompanying drawing for a jet type reactor system, although it applieswith suitable Amodifications to other reactor systems, such as use aturbomixer or other'mechanical mixing means in a Vbottom part of thereaction zone, if desired. l

Referring to the drawing, a fresh feed of the aromatic and olenreactants from feed line I are' preconditioned for thereaction,preferably by :being supplied to a-drying unit, such as'the azeotropicdrying tower 2, in which an aromatic hydrocarbon such as part of thearomatic reactant may act as an entrainer for removing water l commonlypresent in the feed materials. In the same drying unit fresh feed andrecycled arcmatic reactant, from line 3 may be treated at the sameti-me, but the aromatic to olefin ratio isregulated in the mixturestreated. The drying unit may be replaced or supplemented by variousother drying means, such as, alumina driers, calcium chloride driers,etc.

The dried reactant feed mixture withdrawn from the bottom of dryingtower 2 byline 5 is fed by pump 6 through a heat exchange cooling means'l into a bottom part of reactor 8 through a bank of jets 9. The bank ofjets 9 are reaction. With this fresh feed can be returned av requiredproportion of recycled alkylation product being recycled from line I 0,as will be explained, to supply the required high propor- .tion ofaromatic reactant to olen reactant -where i The olenic reactantsYinclude` monomers and polymers of olens. The aromaticcarbon oil phaselayer above the level II. The.

volume of the catalyst sludge or reactionmiigture maintained in thereactor can be` regulated by withdrawing sludge from` the reactor itselfthrough a withdrawal une |12; at'the bottom ofthereactor or some otherpart oa-the reactor belowlevel I I. The quantity of sludgeorreactionVmixe. t

' 'catalyst sludge directly from the reactor 8 through ture contained inthe reactor can'be determined by some type of specic gravity indicatingdei vice, which can be also employed for automatic control ofthecatalyst level.

.Asthe catalyst andl the reactants become ag i, tated ilforintmatecontactin the.catalystfreactionl mix ure,A the hydrocarbon;product passes upward-wv ly rom'y the bottom of the, reactor. throughthe, heavier. reactionmizture phaseA which tends to; settle'fwith'theresult thatthe catalystor sludge, decreases with heightreached. in thereactor; and,- theY alkylation product coliects a relatively,y

quiescent'zone. I4.. llliitha.l givenn sizev circulation Dump,` l e.Dump 6. als liqlld fOW through the' jetsffg canbavariedto increase ordecrease the, efiouvenudee mventory in me reactor and, settling space.Ilfabove theupper level I I A high die intake-f; the. circulating.pumps. Thus, with aevllifieator system. itiSpQSSlble tai/.ary widely.-the catalyst contact time as well. as the. ratio oig aromatic.. is)`olefin., within, the. catalytic reaction zone. ofV theA reactor, this`ratio, beinghereinv termed, internalQarcmatic td olefin ratio, whichdcnendsll the-'amphi Qf-r the allomaticl reactant.

beine. recycled in the p rQduQt from line 1.0 and the aroma-.tic mettant,entering from. line with. the olen reactant. It is important-to. be,ableto-f control this.A lrlterrlall ratio. bye-having.y a. largervolume of. aromatic ,reactantinthe recycled alkylation,product4 from.line I D- than in reactant `feed` from line- 5; sent*4 into Y, the,reactionv zone continu-y o usly.

- Emma Suitablcpoint located,v above the catalystAv level. l Il the,.settled liquid. alkylatlon product as l free 0f. catalystfaspracticable-.is withdrawn from anupper, partei the reactor vessel-1 8through line,

I3; This, withdrawn alkylation productcomprisf. ing. principally the.alkylate,V andv unreacted f aro,. matic. may contain a small ,amount of:entrained catalyst,l sludge, andgsubstances. such as water andhydrogenhalide,v Various means, suchas-a.

screen, knockout baies,y orltering. means `indi-V cated in the upperparto; the reactor 8..-by; Nanay be usedom aid indiminishins the amount.o f en.

trainedcatalystlsludge vcarr-iedodut of Vthereactor through, theA topwithdrawal line,` I 3. With. such modifications for. aiding settlingioutoitheisludge. or. catalyst fromv the alkylationproduct,v evenmechanical mxinedevees, Such. as aturbomixer,

maybe used ,in thebottomofthereactor.. to -agi-V tate the heavierreactionniixture containing-the.A

catalyst,k but it is, advantageous topeliminate me.. chancal :mixingdevices..0i.2tl.1is.. typar The alkylation product withdrawn throughline I3 is divided into two streams, in general the main stream thereofbeing returned through recycle line Ill to pump E for establishing thedesired internal aromatic to olefin ratio and for securing adequatemixing. The other stream of the product is passed through line I8 intoasettler I9 for accomplishing Y removal fof any' entramed small amountof catalyst sludge, which can be withdrawn through a bottom drawoi byline 2l) to be discarded through line 2l Vas spent or be returned partwith. make-up catalyst from a slurry tank 22 by pump 2li in line 23.

lyIakeFup` catalyst may be added to slurry tank 22 through line lfl. orby any convenient feed means. Make-up catalyst may be added, also, to

recycle'ratello'fg the productfrorn line, Idvaluabiy;

catalyst sludge in slurry tank 22 by withdrawing which in general mayincludemeans forneutralizring orremoving residual traces of acidic sub.. stances, suchv as, any traces olif catalyst, or acidic; substances,such as hydrogen chloride, etc.V Washing; with. Caustic usuallyfollowed.. br,A a water washing so that the hydrocarbon material; is,Ithenl suitably conditioned for fractional' distillation which isgthencarried outin one ora series olffractionating towers, e.` g.. towers2,8-,v 2S.; and; 3,9. With the treated alkylation` product; enter-.- ingtower28.. from line, 3lthe relatively volatilef substance, that is 'theunreacted aromatic,y is;

taken overhead to-be returnedrthrough lineydg. Thebottomsioitower/Z.areopassed vbyfline- 32 intof the'negrt-Jfractionation`Zone tower 29 for* stripping outlight', alkylate productmemovedoverhead by.- line 3-3., bottoms fromtower- 29Y areepassedl by line1351mm tha next fractonatnev Zone 0f.; towern 30: fomuhlghazdesiredintermediate alkylaterproduotis taken overhead kthrough line 35 to a;-nsh-- ing unit 3.6. The .heavyalkylate fractioniswithfdrawnas-bottomsfbyline3l from tower30.

To illustrate theimethodwithithe flow plansys-y tem described, ifthe-reactor circulating yDump 6 5 @Hawai-Capacity thatis-,times the:volumeof the reactantieed-ffrom line 5, it can force into the reactor..1 volume ovf this reactantr feed mixture-A, with approximately`Llvolunites of'` the recycled al kylation product (alkylate andunreacted aromatic4 withdrawn from theupperrpart of thefreactor; Ifthesaromatic to olen-volume ratio oi the feedy from line 5.is 2 :l`andif `theiunreactedaromatic is, abouti 55Y Volume per cent-'or therecirculat'ed product,l then the recirculated alkylation product.;entering the,A reactor with'. this feed will supply sufficient4additional aromaticto,` make thei inf ternal aromatic to.olen-.volumeratio about` 10: 1f whichr affordsa betterratio of aromatic to theVoleiin supplied to'thereaction-zone.l On the other -1 hand, if .thearomaticf to. olen volume ratio from. feed line 5fis k2:1 andno-substantial amount Yof 'hyv drocjarbon product' isrecycled,l theresulting Yinternal volume ratio of aromatic to' olefin intheLreaction-zoneis substantially less than 5*:1 and gives anunsatisfactoryproduct unless alargeamount'` offisludge.isarecycledTherefore, it cani be seen that these ratios of aromatic to olefin canbe maintained at a high level, considerably higher than those which arepracticable in any system that employs a once-through hydrocarbon owwith recycling of catalyst sludge to afford a more ilexible control inobtaining a desired alkylate product and yield.

To further illustrate the advantages of the method of the presentinvention with regard to reducing diculties in recovering the products,it is first to be noted that by using a, high recycle of alkylationproduct with an adjusted aromatic to oleiln ratio in the initialV feedfrom line 5, the eiiiuent alkylation product from the reactor 8withdrawn through line I3 can be kept at a low aromatic to alkylateratio. For example, if the feed from line 5 supplies thestoichiometrical proportion of one mole of aromatic per mole of olefinfor mono-alkylation and the recycled hydrocarbon product from line I0increases the proportion of aromatic to a much higher proportion withrespect to the olen reactant, then the eiiiuent hydocarbon product atclose to 100% reaction will contain a relatively low proportion ofunreacted aromatic per mole of net alkylate produced per pass. Thus, thepresent method makes it possible to keep the ratio of aromatic toalkylate in the eiuent hydrocarbon product stream extremely low whilemaintaining the desired high internal aromaticzolen ratio. As aconsequence of this, much less unreacted aromatic is handled in thesubsequent recovery of the alkylate, including chemical treatments,fractional distillation of the unreacted aromatic from the alkylate, andpreconditioning of the thus recovered unreacted aromatic for return withthe fresh feed. This reduction in recovery of the aromatic makes aconsiderable saving in equipment as well as chemicals used in thetreatments. To further demonstrate the feasibility and advantages of theoperation using the procedure of recycling the hydrocarbon product,experimental plant studies were made. The following table presentstypical comparative data and results obtained in this study.

TABLE Eect of recycling hydrocarbon product 'Us recycling sludge[Operating conditions: Reacting benzene and C12 propylene polymer.Temperature 40 F.50F. A1013 catalyst promoted by HCL] Hydro- Sludgecarbon Recycle Product Recycle Inside diameter of jet, mm 3 3 Pressuredrop across jet, p. s. 18. 0 1. 5 Recycled rate, L./Hr 360 105Sludge/Hydrocarbon ratio in recycle 0. 67 0. 08 Mixing energy, HP-Hr./Gal. olefin 0.095 0.002 Composite of total alkylate, Volume percent:

Degradation product 14 14 Detergent alkylate 72 71 Polymer and heavyalkylate 14 15 Yields based on olefin feed, Volume percent:

Total alkylat 126 128 Detergent alkylate 91 91 Sludge product 13 10 Theabove data is representative of a number of comparative tests, includingtests in which the internal volume ratio of aromaticszolei'ln was variedin the range of 3:1 to 300:1.

'It is' of interest to note that the recycling of -the Yalkylationproduct, which includes the unreacted aromatic benzene, with thealkylate does not have any detrimental-eiect with. respect to 6 thereaction selectivityfor producing the desired detergent alkylate(CsHs-CizHzs), although 'it might have been assumed that by recyclingthe alkylate there would be a tendency toward polyd alkylation. Theselectivity was substantially the same with both methods of operation,but a somewhat higher -yield was obtained with the hydrocarbon productrecycling method. Moreover, the alkylation product recycling methoddenitely showed an advantage in greatly reducing the energy requirementlof the recycling' pump, e. g. almost a 50 fold reduction per gallonv ofoleiin reactant in horse-power hours on account of the much greaterdifficulty in pumping' the heavy sludge. At the same time there was theadvantage of a much lower catalyst inventory required in the hydrocarbonproduct recycling operation, making a saving in the relatively expensivecatalyst phase. It was found that the recycling of the hydrocarbonproduct through the jets achieved adequate mixing. By recycling thealkylation product instead of the sludge, a number of other difficultiesare minimized, such as, erosion which is caused by high sludgevelocities, pipe stoppages likely to occur when sludge'is beingrecycled, and corrosion diiculties in pumps, etc.

The foregoing described tests were carried out under conditions whichwere favorable for the sludge recycling operation in order to obtain adirect comparison with regard to the sludge handling problem. However,the operation with hydrocarbon product recycling is stillv moreoutstanding in its advantages when compared'on the basis of its minimumrequirements of aromatic to oleiin in the initial supply `feed, becausethe sludge recycling operation essentially requires a much higher ratioof benzene-olefin in the fresh feed for optimum results, for example, avolume ratio of 5:1, whereas the hydrocarbon product recycling operationlowers this ratio requirement in the fresh feed to the order vof 1:1 to3:1 and thereby lowers the content of aromatic in the alkylation productstream which is sent to the recovery units.

The economical advantages of recycling the alkylation product insuitable proportion to maintain the required excess of aromatic reactantin the reaction zone is illustrated by the following simplifiedexample.:

Y Considering that the minimum aromatic to olen mole ratio required inthe reaction zone is 10:1, the once-through method with recycling ofcatalyst sludge requires nearly this same ratio be maintained in thefeed, and the product would have an approximate composition of: 9 molesunreacted aromatic/1 mole of alkylate. In contrast thereto, by recycling10.5 moles of product, having the composition: 2 moles aromatic/ 1 molealkylate with each mole of olen in fresh feed containing: 3 molesaromatic/ 1 mole olen. With ythe required internal mole ratio of 10:1thus maintained, the product contains only 2 moles unreacted aromatic/ 1mole alkylate. Thus, about twof thirds of the total quantity of thisproduct can be recycled to maintain the required internal aromatic/olenratio while the other third is processed, e. g. by chemical treatmentand distillation to separate vonly 2 moles of unreacted aromatic fromeach 1 mole of alkylate; whereas, with .the method of sludge recycling,over four times the amountof unreacted aromatic has to be processed toseparate 9 moles of unreacted aromatic from each`1 mole of alkylate.Similarlyfthe hydrocarbomproduct recycling method 7E greatly: reducesfthe'loadion-tho Vdraingamits.11.152231f for drying: the fresh :feed.reactants.`

The. lalkylation reaction is.y alrrlost.; instantanef.

ous.l therefore, nearly all 4the olefin, mxadvtthbrentrainment andfolireolaoemeethy fresh* catalyst In the allylationreactions.employing acatalystisludge or emulsion retained in thefreactron. zone, a minorportion ot this catalystiswthdrawnfas spentcatalyst-to be replacedbyrfreshly activated catalyst or catalytic material which' maintanstheneeded catalyst strength. A portion o'fthe spent catalyst tobeseparatedmay be catalyst sludgecarried b y the alkylation prod.; uctyeiiluent from thev reactor intofa separate settler, .or.periodicallyrsludge may he. removed from a' .bottom partof the reactor.

A 'fresh inorganic vhalide active. catalyst, ,such as the aluminum.chloride. complex.,v is vpreferably brought into the reaction` zonebyaddition ofl aluminum chlorideto some of theL sludge, with which itcombines-toforma complex ofhigher specific gravity than 'the .alkylationproduct passed 'upwardly through the reaction zone so that the activeVcatalyst will beretaned .in the reaction zone. The complex ofaluminum'chloride is nearly insolublein the hydrocarbon phase. If 4thefeeds are too dry it is vdesirable to add a small amount of moisture orHC1, ahoutQLZ to 4: weight per cent on A1013 toact asa promoter.

Whatv is termed `catalyst sludge oremulsion generally includes someofthe free catalytic material',:su'ch `as AlClcyand the/catalyticmaterialr combined or associated'withjthe reactants gor polymersV of theolefin. In using` other vinorganic flalidei'oaialysts saches BES,HFrQte, 'Such Cata.- lysts similarly are- 'use'din --`a for-mA of aheavylidui'dfemulsion or sludge, that-settles cutoff-the reaction mixture tobe retainedaat- *the j' bottom ofthe reaction vessel-and similarreactionfjconditions'fare used;

already indicated, kvit has lbeen Yfoundj-best for 'the `purpose of thelpresent methodv to add thefresh-aluminum chloride to a smallfportionoft-he spentr catalyst "mixture ratherfthanl-to the reactants for freplenishing the active'ica'talyst-:inthefreactionzone,-beoausesadditionsotfthecata lystto the reactants :tendstosolubilizefthefcataly'stf ytherein .and thusfaactsz-:unavorabl-y.@against retentionfofaeatalyst sludgenvithin; the reaction'f zone.

iThe alkylation reaction.y conditions ofsordinary. ranges.. of:.teniperatm-'es i and .pressures .cariche used, e.. g. :temperatures of'aboutfe-E.; to; 1:15?

F, .op '.hi'gher, atmospheric for superatmospherio- 8.reactants.:mammie-.liquidschas. contact .-.ne.r.iod .is preferably forexample.. '1, toQ/.xninuiea alliylatioareaotionsvw.. reactants, aromaticreactants, Aa. catalysts. vPrc ferably.the.- olefin reac aStraight-.chain lfsfliehtly bra" from v11,110.2;.1 carbonato@ nmainlygive mono-alkylat actant usine @1.1i .of .f1.1 form .heaviercomplexes m inaugural-aimante product l howeyer., can be".adaptdor.alky1ati-o'V l' loWerbleln .reactants that'gt'erfdito.givev su sttialy amounts of polyallgylaftion',becauseLth p alkylation` is reducedby 'increasing lfthe. .a ic olenratio infjthfe. reaction zori, andthepoly allylate product v. after being separated from'v mono-.alkylatecanbereturnedto the` zone.

Whatisclaimed is.:

'1. In .a process foralkylating analkylatable v aromatic compound of theclass `co'njsistiifig off benzene and toluene Witha Onto C2i ole bycontactwith an inorganicpalidej aikyiepicnfcal-M lystunderl allaylationconditions', the improve:

' mixture, andpassing the resultingffleed mixtu ment which comprisesadmixingfthep actant withat least a stQChom trical e proportion ofaromatic. aotant to'l together With the` reyoled str elarn oflalliSiate4i productrand unreacted aromaticintofa reaction zone whereinthealliylation catalyst is retained asa sludge in a heavy reactionmixtureysav-id recycled alkylation product Supplying' an'egio'essf ofthe aromatic reactant, dispersing ther thus' introduced mixtureof Vthereactants and alkylate into .the heavy reactionvmixture,jstiat-if-yf1ng''a resulting alkylation product liquid phas'"com prising principally alkylate and uhreactedv romatic above, theheavyrreaction mixture wh' retains thecatalyst inabottom partfof'saiaction zone, withdrawing the allylation product. thus stratified,separating alkylat from aiino'r portion of the thus Withdrawn product,and returning a remaining major portion of the withdrawnproduct. assaidrecycled .,stream. y

2. In a processdened by claim 1, dispersing the mixture of reactants andrecycled products inthe form of aplurality of-doWnwardly-drected jetsinto the heavy reaction mixture'to Aagitate the, reaction mixture, andsettling out catalyst fromthe hydrocarbon product collected in arelativelyouiescent liquid body stratied above said heavy reactionmixture in which the catalyst is retained.

3. In a vprocessv as 'defined by .claimY 1, the 13e,v cycled allgylationVproduct being in'large'r volume than theteed mixturepassedvintogthe,react zone.

' 4. In yeti-process as defined by claimr Lthel recycled alkylationproduct v -being passedr intolthe reactionzone at a rate'Vwhich'isat':least four' times the volumewof saidv feed mixturepassinginto the reaction zone per unit of timefan'd the alkylate is separatedfrom a minor portion of the alkylation product.

L5.. v-A process lfor .alkrlating an ,.aliadatableV aromatic .compoundof the class consisting of Ibenzene and toluene with a Cfrrto G2 olefinhyE Contact with an inorganic halide altr-lation catalyst underalkylationconditions, which. comprises. crying 1 roaant :mixture of-.the olen f ao. aromatiofto.; be..l reacted; :i111 -a-.reaotion 9119imixing the dried reactant mixture with an alkylation product containingalkylate being formed and unreacted aromatic withdrawn from the reactionzone, passing the resulting mixture into intimate contact with a heaviermixture of the catalyst maintained as a sludge in said reaction zoneunder alkylating conditions, separating a resulting alkylation productof alkylate and excess aromatic reactant from the catalyst, retainingsaid catalyst in the reaction, separately withdrawing a portion of thecatalyst as it becomes spent from the reaction zone, replacing thewithdrawn portion of spent catalyst by a similar volume of reactivatedcatalyst, recycling a major portion of said product freed of catalystfor the admixing therewith of the dried reactant mixture, and removingthe net alkylate produced per pass from a minor portion of said product.

6. A vprocess for alkylating -an alkylatable aromatic hydrocarbon of theclass consisting of benzene and toluene with a C11 to C21 olen bycontact with an inorganic halide alkylation catalyst in the form of asludge under alkylation conditions, which comprises passing a feedmixture stream containing between 1 and 5 volumes of the aromatic pervolume of olen into a reaction mixture containing the catalyst,simultaneously mixing with said feed stream a larger volume proportionof a recycled stream of alkylation product containing alkylate andunreacted aromatic withdrawn from said reaction zone and substantiallyfreed of the catalyst, injecting said mixed streams into the reactionmixture agitated thereby in a reaction zone below a more quiescentsettling zone in which alkylation product collects, withdrawing thealkylation product substantially freed of catalyst sludge from saidsettling zone, returning a major portion of the withdrawn alkylationproduct as said recycled stream, treating a minor portion of saidwithdrawn alkylation product to recover alkylates therefrom.

7. A process for alkylating benzene with C12 polypropylene by contactwith an aluminum chloride complex sludge catalyst retained in a reactionzone under alkylation conditions, which comprises passing a feed mixturestream containing between 1 and 5 volumes of benzene per volume of thepolypropylene into a body of the sludge catalyst contained in a bottompart of the reaction zone, admixing with said feed stream a largervolume proportion of a recycled stream of alkylation product containingalkylate and unreacted benzene withdrawn from a settling zone above saidreaction zone, collecting alkylation product from the reaction zone inthe settling zone above the catalyst sludge, withdrawing said alkylationproduct from said settling zone, returning a major portion of thewithdrawn alkylation product as said recycled stream, treating a minorportion of said withdrawn product to recover alkylate therefrom,separately withdrawing a portion of the catalyst sludge as it becomesspent from said reaction zone, dissolving aluminum chloride in a portiono1" the withdrawn spent catalyst sludge until the sludge containsbetween and 45 weight per cent of combined aluminum chloride and is thusreactivated, and replacing the withdrawn portion of the spent catalystby a similar volume of the thus reactivated catalyst sludge.

8. A process for allrylating benzene with a C11 to C21 olefin by contactwith an inorganic halide alkylation catalyst in the form of a sludgeunder alkylation conditions, which comprises passing a feed mixturestream of up to 3 moles benzene per mole of the olen into a reactionmixture containing the catalyst under alkylation conditions, mixing withsaid feed stream a larger volume proportion of a recycled stream ofalkylation product containing benzene alkylated by the olefin andunreacted benzene withdrawn from said reaction zone for increasing thearomatic to olefin ratio therein to at least 10:1, agitating thereaction mixture in the reaction zone by injecting the mixed streamsbelow a more quiescent settling zone in which alkylation product andunreacted benzene collect, withdrawing alkylation product and unreactedbenzene from said settling zone, returning a major portion of thealkylation product with unreacted benzene withdrawn from said settlingZone as said recycled stream to the reaction zone, treating a minorportion of said withdrawn alkylation product to recover alkylatetherefrom, retaining the catalyst in the reaction zone except for aportion thereof which is withdrawn to be reactivated and returned to thereaction zone and except for a portion which is withdrawn as spentcatalyst.

WALTER J. PALTZ. BRUCE R. TEGGE.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 2,373,062 Stahly Apr. 3, 1945 2,388,007 Pardee et al Oct. 30,1945 2,388,758 Mills, J1'. NOV. 13, 1945 2,404,340 Zimmerman July 16,1946 2,426,611 Hudson et al Sept. 2, 1947 2,437,356 Hill Mar. 9, 19482,448,641 Whitman Sept. 7, 1948 2,477,382 Lewis July 26, 1949 2,498,567Morris et al Feb. 21, 1950

1. IN A PROCESS FOR ALKYLATING AN ALKYLATABLE AROMATIC COMPOUND OF THECLASS CONSISTING OF BENZENE AND TOLUENE WITH A C11 TO C21 OLEFIN BYCONTACT WITH AN INORGANIC HALIDE ALKYLATION CATALYST UNDER ALKYLATIONCONDITIONS, THE IMPROVEMENT WHICH COMPRISES ADMIXING THE OLEFIN REACTANTWITH AT LEAST A STOICHIOMETRICAL EQUIMOLAR PROPORTION OF AROMATICREACTANT TO FORM A FEED MIXTURE, AND PASSING THE RESULTING FEED MIXTURETOGETHER WITH THE RECYCLED STREAM OF ALKYLATE PRODUCT AND UNREACTEDAROMATIC INTO A REACTION ZONE WHEREIN THE ALKYLATION CATALYST ISRETAINED AS A SLUDGE IN A HEAVY REACTION MIXTURE, SAID RECYCLEDALKYLATION PRODUCT SUPPLYING AN EXCESS OF THE AROMATIC REACTANT,DISPERSING THE THUS INTRODUCED MIXTURE OF THE REACTANTS AND ALKYLATEINTO THE HEAVY REACTION MIXTURE, STRATIFYING A RESULTING ALKYLATIONPRODUCT LIQUID PHASE COMPRISING PRINCIPALLY ALKYLATE AND REACTEDAROMATIC ABOVE THE HEAVY REACTION MIXTURE WHICH RETAINS THE CATALYST INA BOTTOM PART OF SAID REACTION ZONE, WITHDRAWING THE ALKYLATION PRODUCTTHUS STRATIFIED, SEPARATING ALKYLATE FROM A MINOR PORTION OF THE THUSWITHDRAWN PRODUCT, AND RETURNING A REMAINING MAJOR PORTION OF THEWITHDRAWN PRODUCT AS SAID RECYCLED STREAM.